The central limit theorem

Introduction to Statistics

George Boorman

Curriculum Manager, DataCamp

Rolling a die five times

six sided die.png

Roll Result
1 1
2 3
3 4
4 1
5 1

 

$Mean(Results) = 2 $

Introduction to Statistics

Rolling a die five times

Roll Result
1 4
2 4
3 5
4 3
5 6

 

$Mean(Results) = 4.4 $

Roll Result
1 1
2 3
3 1
4 5
5 6

 

$Mean(Results) = 3.2 $

Introduction to Statistics

10 sets of five die rolls

  • Roll a die five times
  • Record the mean
  • Repeat 10 times
Set Mean
1 3.8
2 4.0
3 3.8
4 3.6
5 3.2
6 4.8
7 2.6
8 3.0
9 2.6
10 2.0
Introduction to Statistics

Sampling distributions

Sampling distribution of the sample mean

histogram_of_ten_sample_means.png

Introduction to Statistics

100 sample means

histogram_of_one_hundred_sample_means.png

Introduction to Statistics

1000 sample means

histogram_of_one_thousand_sample_means.png

Introduction to Statistics

10000 sample means

histogram_of_ten_thousand_sample_means.png

Introduction to Statistics

100000 sample means

histogram_of_one_hundred_thousand_sample_means.png

Introduction to Statistics

One million sample means

histogram_of_one_million_sample_means.png

Introduction to Statistics

Central limit theorem

The sampling distribution of a statistic becomes closer to the normal distribution as the size of the sample increases.

histograms of 10, 100, and 1000 sample means, where higher number of sample means has a more bell-curve shaped distribution.png

* Samples should be random and independent

Introduction to Statistics

Standard deviation and the CLT

histogram_of_one_hundred_thousand_sample_standard_deviations.png

Introduction to Statistics

Proportions and the CLT

Roll Result
1 2
2 1
3 4
4 2
5 6

 

  • $\frac{1}{5}$ or 20% are a 4
Set Mean
1 4
2 4
3 1
4 4
5 3

 

  • $\frac{3}{5}$ or 60% are a 4
Introduction to Statistics

Sampling distribution of proportion

distribution_of_sample_proportions_also_looks_normal.png

Introduction to Statistics

Mean of the sampling distribution

Sampling distribution of sample means with dashed line down the middle.png

Introduction to Statistics

Benefits of the central limit theorem

central_limit_theorem_workflow.jpg

Introduction to Statistics

Let's practice!

Introduction to Statistics

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